Recently, a cloud service for providing computing resources such as virtual machines and storages to users through a network is widely used. A user of a cloud service can reduce costs for possession and management of computing resources by renting computing resources from a service provider. Patent Literature 1 describes an example of an exemplary embodiment of the cloud service.
With an increase in the number of users of a cloud service, the number of users affected by a service failure also increases. In a large-scale cloud service, hundreds of thousands of users may be affected by a partial system failure. However, the user cannot directly control failure recovery processing because the user cannot know the configuration and management method of the cloud service and the details of the failure. The user has to wait until the service is available again since the failure is eliminated by the cloud service provider.
Inability to know the detailed situation of failure recovery causes the aggravation of the anxiety of the user. Therefore, there is a possibility that access such as queries from users and retrial by users will rush. A rapid increase in access from users causes a new trouble such as system performance degradation and function loss. In order to alleviate the stress of a user associated with such a service failure, Web sites called a “dashboard” are provided by some cloud service providers. Through the Web site, efforts for service recovery are disclosed to the users.
Patent Literature 2 describes a method for disclosing failure information by generating a Web page for disclosing the failure information, based on the failure information received from a user. By quickly disclosing failure information through Web in the event of a failure, the stress of a user affected by the failure can be alleviated.
Also, Patent Literature 3 describes a failure notification method for notifying network failure information to a user. The failure notification method described in Patent Literature 3 notifies failure information to each user by e-mail or the like based on an application reservation status of the user when a failure occurs in a system associated with communication such as a videoconference application. This method determines an affection on the user and notifies failure information, based on an application reservation period of the user and a temporal overlap of the period from failure occurrence to failure recovery.
Also, Patent Literature 4 describes a method for notifying necessary information to a user when a network service is unavailable. In the method described in Patent Literature 4, a server machine manages identification information of a client machine using a resource provided in a network service, the type of a program operating in the client machine using the resource, and the type of a user of a program of the client machine. When the network service is unavailable due to the occurrence of a predetermined problem in the resource of the server machine, network service information based on the resource provided in the network service is notified to the client machine.
Also, NPL 1 discloses a current state of a cloud service provided in Google (registered trademark) AppEngine. Also, NPL 2 discloses a current state of a cloud service provided in Amazon (registered trademark) EC2. When a failure occurs in the cloud service, a failure occurrence place, a service recovery schedule time, and the like are disclosed in the Web site. Since the information is updated in accordance with a service recovery status, the user can provide for service resumption with reference to this site.
Also, Patent Literature 5 describes a method for monitoring a data recovery available time in a storage system that performs asynchronous remote copy between a plurality of storage devices. In the method described in Patent Literature 5, the newest or equivalent data retained in a buffer of a first storage device are accumulated at predetermined time intervals together with time information. A recovery time is calculated with reference to a predetermined time based on at least one of the accumulated information, the oldest or equivalent data at a predetermined time, and the number of accumulated data by using data stored in a second storage device.